It is a requirement of any good JavaBean, according to the JavaBean spec, to implement Serializable. Hibernate won't cough up locally if you don't explicitly add the 'implements' but you might run into problems later on when you go into production and start passing around entities between cluster members.
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com
subject: org.hibernate.MappingException: table refers to an unmapped class